The present invention relates in general to processes and systems for protecting tool joints, machined surfaces, and other worked or shaped end formation of elongated articles, and more particularly to methods and apparatus for protecting tool joints and machined surfaces of elongated articles such as oil well drill pipe, drill collars, casings, tubing, subs and various oil field machined goods against water and moisture damage to such articles and against water and moisture entrusion into grease that may be used to protect the machine surfaces.
Oil field tubular goods, such as subs, drill pipe, casing, tubing, drill collar, line pipe and the like have connections on their ends that are threaded or otherwise shaped by machining which are extremely vulnerable to rusting and pitting. The problem is particularly acute in regard to storage of inventory supplies of such oil field tubular goods, which, in order to meet unpredictable varying demands, may be very great at one period of time and relatively slight at other periods of time, such that suppliers of such processed oil field tubular goods frequently have large quantities of them stacked in storage yards where they are exposed to the elements.
Heretofore, it has been a frequent practice to coat the machined threaded surfaces or the like with grease, dope, oil, or the like, as is well known in the industry, in an effort to protect the machined or threaded surface from damage by adverse weather conditions, but this technique of attempted protection of the threaded or machined surfaces has failed to achieve the desired goal with disturbing frequency. No matter how much grease, dope or oil is applied to the threaded or machined connection end portion of the oil field tubular goods, the effects of weather, hot sun and driving rain on such articles stacked in storage yards cause the protection to loose its protective coating, or water or moisture may penetrate through the grease, dope or oil and cause the threaded connection to rust. Either way, damage results to these threaded connections, such that such tubular goods must be cleaned and reprotected periodically with grease or oil, or oil type compounds, at considerable expense. Also, because of the knowledge gained from experience that the threaded machined portions of the tubular goods frequently become damaged during storage, the expense and inconvenience of regular inspection of the stored supplies of such pipes, casings and the like becomes necessary. If the rust is allowed to continue for any length of time, damage to the threaded area becomes so severe that the threaded ends of the tubular goods will have to be recut before they are delivered to the user.
Another problem arises in connection with the storage of such threaded or machined oil field tubular goods arising from accumulation of moisture in the hollow bores of the pipes or casings caused by their being partially sealed but not hermetically sealed, such that moisture accumulation occurs within the bore of the pipe or casing which causes rust or corrosion rendering the article unsatisfactory for use.
An object of the present invention, therefore, is the provision of a novel process and system for protecting such oil field tubular goods such as subs, drill pipe, casings, tubing, drill collars, line pipe and the like having threaded or machined end coupling portions, against rust, pitting and moisture induced corrosion damage, wherein the machined, threaded or tool joint area of such tubular product is encased and protected against weather and moisture attack by a shrinkable plastic wrapping enveloping end portions of the machined tubular products protecting them by a shrink wrap encasement of low density polyethylene film or the like.
Another object of the present invention is the provision of a novel process and system for protecting the end portions of oil field machined tubular products or the like as defined in the immediately preceding paragraph against moisture or weather damage causing corrosion, rust and the like, wherein the portions of the ends of the machined tubular product having threaded, machined or otherwise cut surfaces are first coated with grease, dope or like protective compounds over the machined surface portions thereof and are then encased in a shrinkable plastic film of low density polyester or the like extending entirely over the machined and grease coated area and extending beyond onto undisturbed and uncoated adjoining portions of the tubular pipe, casing or other product and which is shrunk in place to form an air-tight shrink wrap shielding the machined surface portion from driven rain, moisture and the like.
Yet another object of the present invention is the provision of a novel process and system for protecting threaded, machined or cut end portions of oil field tubular products as described in the two immediately preceding paragraphs from rain, moisture and damage effect from weather or climatic conditions, wherein one or more rings of sealing materials such as grease, silicone, putty or the like is/are formed on the exterior surface of the pipe, casing or tubular product spaced a short distance toward the mid-region thereof from the machined surface portion and the machined surface portion and ring or bead of material is enclosed in a shrinkable bag or wrap film of low density polyethylene or other plastic material by application of heat to form a shrink wrap providing a shield for protecting the enclosed tubular product portion from attack by moisture, rain wind, or the like.
Still another object of the present invention is the provision of a novel process and system for protecting threaded or machined end portion of oil field tubular products as defined in any of the three preceding paragraphs, wherein moisture accumulation within the interior of the tubular product is prevented by providing a vent tube, hose or the like in at least one end of the tubular product extending through the wall of the shrink wrap film material and extending far enough into the bore of the pipe, casing or tubular product to allow air to circulate and keep moisture from accumulating near the threaded area, or, after one end of the pipe or tubular product is sealed, an inert gas can be supplied to the vent tube to purge the interior of the pipe of oxygen, after which the vent tube can be quickly sealed to minimize corrosive condition in the interior of the tubular product during storage.
Other objects, advantages and capabilities of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings illustrating a preferred embodiment of the invention.